20561299 has 4 divisors (see below), whose sum is σ = 22430520. Its totient is φ = 18692080.

The previous prime is 20561291. The next prime is 20561311. The reversal of 20561299 is 99216502.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 20561299 - 2³ = 20561291 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20561291) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 934594 + ... + 934615.

It is an arithmetic number, because the mean of its divisors is an integer number (5607630).

Almost surely, 2^20561299 is an apocalyptic number.

20561299 is a deficient number, since it is larger than the sum of its proper divisors (1869221).

20561299 is a wasteful number, since it uses less digits than its factorization.

20561299 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1869220.

The product of its (nonzero) digits is 9720, while the sum is 34.

The square root of 20561299 is about 4534.4568583238. The cubic root of 20561299 is about 273.9577029920.

It can be divided in two parts, 205 and 61299, that added together give a square (61504 = 248²).

The spelling of 20561299 in words is "twenty million, five hundred sixty-one thousand, two hundred ninety-nine".